Question

Which sentence correctly uses commas to separate the elements of a date?

Answer 1

The correct sentence would be:
D: The Carl G. Jung exhibition runs from June 17 to September 25, 2010.
You always have to add a comma after the date/before the year.
It is not necessary to add the comma after June 17 since you are already adding the comma to one of the dates and plus it doesn't have a year to it.

Answer 2

"...June 17 to September 25, 2010."

The last one because the comma is only needed after the day and before the year.